The City of London, dark and rainy.
Out of nowhere, a mysterious terrorist group appears and instigates an armed uprising.
After taking the Prime Minister, his family, and other high-ranking politicians hostage at the Prime Minister's home, they issue a single demand.

"Bring Ryu Hayabusa."

Ishigami and Mizuki, special officers in Japan's Ministry of Defense, inform Ryu of these events, who then accompanies them to London.
After cutting a path through a relentless onslaught waged by the terrorists, Ryu finds himself face to face with their leader, the Regent of the Mask.
Following a ferocious battle, Ryu thought he had fatally wounded his opponent, only to find that his right arm had been cursed with the Grip of Murder: a seal powered by the grudges of all those Ryu has killed.
Left unchecked, the curse will eat away at Ryu's arm, then continue until it has consumed his entire body and robbed him of his life.
With the curse weighing Ryu down and preventing him from fighting at his full strength, the Regent of the Mask declares war on the entire world.

Will Ryu die before he can stop the world from ending?

Feeling the weight of every life he has taken more heavily than ever, Ryu presses on to stop the terrorists' evil plans.